Catalyzed condensation of aromatic compounds with unsaturated organic compounds



Patented Feb. 23, 1954 CATALYZED CONDENSATION OF AROMATIC COMPOUNDS WITH UNSATURATED OR- GANIC COMPOUNDS Herman Pines and Vladimir N. Ipatiefl, Chicago,

111., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. Application July 25, 1951, Serial No. 238,566

17 Claims. (Cl. 260-668) This invention relates to the condensation of unsaturated organic compounds with aromatic compounds and to products formed thereby. This invention relates more particularly to the side chain alkylation with an olefin of an alkylaromatic hydrocarbon in which a carbon atom combined with the aromatic nucleus is also combined with a hydrogen atom. The process relates more specifically to the side chain alkylation with ethylene of an alkylbenzene hydrocarbon having at least one hydrogen atom combined with a carbon atom in alpha position to the benzene ring.

The condensation of aromatic compounds with unsaturated organic compounds such as the alkylation of aromatic hydro-carbons with olefinic hydrocarbons, has been the subject of many investigations over a long period of time. Many different catalysts have been used including various mineral acids and acid-acting compounds but in all of these reactions, nuclear condensation has always been effected. Thus in the acid catalyzed alkylation of aromatic compounds having attached to a carbon atom of the rin a saturated carbon atom to which is attached at. least one hydrogen atom, the entering alkyl group attaches to the aromatic nucleus. The present process relates to a novel method of introducing the alkyl group into the side chain of an alkylaromatic hydrocarbon. Heretofore we accomplished side chain alkylation of toluene and related alkylaromatic compounds by noncatalyzed thermal means as set forth in our copendin-g application Serial Number 152,991 filed March 30, 1950, but this thermal alkylation process requires high temperatures and high pressures for its successful operation.

We have now found that side chain alkylation of toluene and other carbocyclic aromatic and heterocyclic aromatic ring compounds having a 'non-olefinic double bond such as pyridine, quinof a catalyst comprising essentially an alkali metal and an acetylenic hydrocarbon. The carnon atom which is attached to the aromatic nucleus of said aromatic compounds is referred to as a "saturated carbon atom because itis a 'part of a non-olefinic group such as an'alkyl group, a cycloalkyl group, an aralkyl group, or

" an aryl group containing no ethylenic bonds or similar unsaturation. The carbon atom which is attached to an aromatic nucleus is thus a part of a saturated group including an alkyl group, a cycloalkyl group, and an aralkyl group (as a CsH5CH2- group) containing no olefinic unsaturation.

An object of this invention is to react an unsaturated organic compound with an aromatic compound selected from the group consisting of carbocyclic and heterocyclic aromatic ring compounds having attached to a nuclear carbon atom a non-olefinic or saturated carbon atom to which is attached at least one hydrogen atom.

An additional object of this invention is to react a mono-olefin with an alkylaromatic hydrocarbon to form an aromatic hydrocarbon with a longer alkyl group.

Another object of this invention is to condense ethylene with the side chain of an alkylaromatic hydrocarbon having attached to a nuclear carbon atom a carbon atom of said alkyl group to which is attached at least one hydrogen atom.

Still another object of this invention is to condense ethylene with the alkyl side chain of an alkylbenzene hydrocarbon, said side chain containing an alpha carbon atom to which is attached a replaceable hydrogen atom.

A further object of this invention is to condense ethylene with the cycloalkyl group of a cycloalkylbenzene hydrocarbon, said cycloalkyl group having a hydrogen atom combined with the carbon atom of the cycloalkyl group which is attached to the aromatic ring.

A still further object of this invention is to provide a process for the side chain alkylation of an alkylaromatic hydrocarbon.

A further object of this invention is to condense ethylene with a polycyclic hydrocarbon having at least one of the rings saturated and having at least one hydrogen atom combined hydrocarbon and an aromatic compound selected from the group consisting of carbocyclic aromatic and heterocyclic aromatic ring compounds having attached to a nuclear carbon atom a carbon atom of a hydrocarbon group selected from the group consisting of an alkyl group, a cycloalkyl group, a cycloalkalkyl group, and an aralkyl group andto which last named carbon atom is attached at "least one hydrogen atom, the process being carried out at condensation conditions in the presence of an alkali metal and an acetylenic hydrocarbon, and recovering the resultant condensation product.

A second embodiment of this invention relates to a process which comprises reacting an olefinic hydrocarbon and an aromatic compound selected from the group consisting of car-bocyclic aromatic and heterocyclic aromatic ring compounds having attached to a nuclear carbon atom a carbon atom of a saturated hydrocarbon group and to which last named carbon atom is attached at least one hydrogen atom at condensation -conditions in the presence of an alkali metal and an acetylenic hydrocarbon capable of reacting with said alkali metal to form an alkali metal acegtyjlifie, and recovering the resultant condensation product.

QAnother embodiment of this invention relates to a process which comprises reacting a monoolefin and an aromatic compound having attached to a nuclear carbon atom a carbon atom of a saturated hydrocarbon group and to which last named carbon atom is attached at least one illydrogenatom at condensation conditions in the vpresence of an alkali metal and an acetylenic "lhydrocarbonhaving hydrogen combined with a ,carbon atom of the CEC- group, and recover- .ingf theresultant condensation product.

"Still another embodiment of this invention relates to a pi'ocessfor producing longer chain aromatic hydrocarbons which comprises reacting -anallrenc and an aromatic hydrocarbon having attached to ainuclear carbon atom acarbonatom of .the '-CEC- group, and recovering the resultan't "longer chain aromatic hydrocarbons.

A .turther embodiment of this invention relatesfto a process 101' producing a longer chain ,benzene hydrocarbon which comprises reacting ,anfialkene and abenzenerhydrocarbon having at- }tachedfto a nuclear carbon atom a carbon atom of a saturated'hydrocarbon group and to which last named carbon atom is attached at least DnehydrOgen atom at a condensation temperature in the presence of a catalyst comprising essentially sodium and an acetylenic hydrocarbon with the formulaRCECH wherein R represents, a member of the group consisting of hydrogen ja'nd a'saturated hydrocarbon group, and recovering the resultant longer chain benzene hydrocarbon.

A still further embodiment of this invention relates'to a process for producing a longer chain benzene hydrocarbon which comprises reacting ethylene and a benzene hydrocarbon having attached to a nuclear carbon atom a carbon atom of a saturated hydrocarbon group and to which last-named carbon atom is attached at least one hydrogen atom at a condensation temperature in T the presence of a catalyst comprising essentially an alkali metal and a mono-alkyl acetylene, and recovering a longer chain benzene hy- Jdrocarbon from the resultant reaction product.

An additional embodiment of this invention relates to a process for producing a longer chain benzene hydrocarbon which comprises reacting ethylene and a benzene hydrocarbon having attached to a nuclear carbon atoma carbon atom of a saturated hydrocarbon group and to which last named carbon atom is attached at least one hydrogen atom at a condensation temperature in the presence of a catalyst comprising essenjtiallysso'dium and a mono-alkyl acetylene, and recovering a longer chain benzene hydrocarbon from the resultant reaction products.

A still additional embodiment of this invention relates to aprocess which comprises catalytically reacting a non-conjugated olefinic hydrocarbon and an aromatic hydrocarbon having a structure represented by the formula:

Ar +R 3 wherein Ar represents an aromatic radicalhaving a nucleus selectedlfrom carbocyclic and heterocyclic nuclei and .R and R each separately and independently represents .a member of the group consisting of a :hydrogen atom, an alkyl group, a cycloalkyl group, and anaryl .group andRand P. together with the carbon atom 'to whichthey are bound represent a cycloalkyl .group, the process being carried out at a condensation temperaturein the presence QLacatalyst comprising essentially an alkali metal and an acetylenic'hydrocarbon, and recovering the resultant condensation product.

Still another embodiment of .this inventionre- 'lates to a process for producing normal propylbenzene which-comprises reacting ethylene and toluene at a condensation temperature in the presence of a catalyst comprising essentially sodium and a mono-alkyl acetylene, and recovering normalpropylbenzene drom theresultant reaction product.

The compounds with which-unsaturated organic compounds-are-condensed in this process comprise aromatic-compounds having attached tola nuclear carbon atom a carbonlatom ofasaturatedhydrocarbon group .to which last named .carbonatom is attachedatrleast one hydrogenatom. .By the term aromaticecompound we mean to includenot only alkylated benzenes, -subst'itued benzene-s,

, substitutednaphthaleneaand vderivatives thereof,

but also all-compoundsccntaininga stable ring or nucleus such as is present in benzene and which possesses :unsaturation :the sense that benzene does, but which has-no ethylenic unsaturation. Consequently, it can be seen that the term .aro-

matic compound, in thesense in Whichit is used in the specification and the appended claims,

includes not only .carbocyclic compoundsbut also .heterocyclic compounds having stable nuclei.

The carbocycliccompounds may have a benzene, naphthalene, etc. nucleus, The heterocyclic-arcmatic compounds 'may have a pyridine, iuran,

thiophene, ,pyrrole, pyrazole, -etc., nucleus. In addition, the :aromatic compounds contemplated for use in our processmay'contain both a carbocyclic ring and 1a -heterocyclic ring suchlas is found in indole and in carbazole. --A lso, the arc- =matic compounds may contain both a benzene pounds preferred :for use in this process contain a saturatedside chain,-said chain being attached ,to a nuclear carbon atom :by; a saturated carbon atom, i. e., a carbon atom that is bonded by univalent bonds to four atoms. The saturated carbon atom should have .at least one hydrogen atom attached thereto. These requisites are desirable for the reason that aromatic compounds, such as t-butylbenzene and t-amylbenzene, which do not have a hydrogen atom attached to the alpha carbon atom, show very little tendency under the conditions of operation employed in this process to undergo condensation of the type herein taught. Similarly, styrene, in which the alpha carbon atom in the side chain is unsaturated, does not condense with unsaturated organic compounds in the manner herein specified. Thus the preferred aromatic'compounds are those in which the alpha carbon atom of the side chain i saturated and in which said alpha carbon atom has at least one hydrogen atom attached thereto. The side chain may comprise only one carbon atom, as the methyl group in toluene, or it may comprise a number of saturated carbon atoms in straight chain or branched chain relation such as the normal butyl radical or the isobutyl radical in normal butylbenzene and isobutylbenzene, respectively. The chainneed not necessarily be an aliphatic chain; it may be a cycloalkane chain as in tetralin or as in cyclohexylbenzene or an aralkyl group as a benzyl group as in diphenylmethane. 7

Suitable alkylaromatic hydrocarbons include toluene, ethylbenzene, normal propylbenzene, cumene, normal and secondary butylbenzene, methylnaphthalene, and the like. Other suitable aromatic hydrocarbons include tetralin, indan, diphenylmethane, cyclopentylbenzene, and methylethylbenzene.

The aromatic ring in the compounds herein referred to may contain other substituents such as a chloro group, a methoxy group, an ethoxy group, a nitro group, and the like.

The aromatic reactants employed in our process are condensed with unsaturated organic compounds. The unsaturated organic compounds are olefinic in character and include monoolefins, particularly ethylene, diolefins and other poly-olefins. For the purposes of this invention, aromatic compounds such as benzene are not regarded as being unsaturated. Examples of unsaturated organic compounds suitable for use in this process include mono-olefins such as ethylene, propylene, l-butene, Z-butene, and isobutylene, mono-olefins of higher molecular weight; non-conjugated dienes such as 2,5-dimethyl-1,6- hexadiene and non-conjugated poly-olefins containing more than tWo pairs of double bonds per molecule; unsaturated ketones such as mesityl oxide, and compounds such as allyl amine, allyl cyanide, acrylonitrile, alpha cyanoacrylonitrile and the like.

Catalysts which are useful in this process include a combination of alkali metals and acetylenic hydrocarbons and preferentially those which react with alkali metals to form alkali metal acetylides. Such acetylenic hydrocarbons include acetylene, methylacetylene, ethylacetylene, pentine, hexine, heptine, and also other acetylenic hydrocarbons containing the CECH group. Of the alkali metals: lithium, sodium, potassium, rubidium'and' cesium; the more plentiful sodium and potassium are generally preferred and particularly sodium because .of its relatively lower cost. These alkali metals areutilized together with one or more acetylenic hydrocarbons to form catalysts. The presence of both an alkali metal and one or more of the acetylenichydrocarbons is necessary for. effecting the combinaprogresses.

6 tion or condensation of an olefin such as ethylene with the alkyl side chain or other saturated side chain of a carbocyclic or heterocyclic aromatic ring compound having attached to a nuclear carbon atom a saturated carbon atom to which is attached at least one hydrogen atom.

Better contacting of the reactants and catalysts and improved yields of desired products are sometimes effected by mixing the alkali metal and acetylenic hydrocarbon catalyst mixture with a catalyst supporting or spacing material such as activated charcoal, also granular coke, silica, alumina, pumice, porcelain, quartz, etc.; steel turnings, copper shot, etc. which do not have an adverse influence on the reaction but improve the mixing. Such spacing materials are useful in either batch type operation as in an autoclave or in continuous treatment in a tubular reactor or other suitable apparatus.

The process of this invention is carried out using either batch or continuous types of operation in suitable equipment such as autoclaves or tubular reactors constructed from steel or glass lined steel reactors. The process is carried out at a temperature of from about to about 350 C. and preferably at a temperature of from about 150 to about 275 C. at a pressure of from about 5 to about 50 atmospheres. When the stirring or mixing of the reactants and catalyst is very thorough and efficient, the process may be carried out readily at a temperature of C. and at a pressure of 5 atmospheres, but higher temperatures and pressures are preferred when the mixing is less eificient. The operating temperature and pressure will also be dependent upon the aromatic and olefinic hydrocarbons charged and upon the ratios of reactants present in the reaction zone; as well as upon the catalyst present.

In order to promote the primary side chain alkylation, that is, to attach only one alkyl group to the alkyl side chain and in some instances to decrease the loss of olefin through undesired side reactions, it is generally preferred to employ an excess of aromatic hydrocarbon to olefin such as ethylene in this process. In other words, the preferred ratio of aromatic hydrocarbon to olefinic hydrocarbon is greater than one.

The amount of catalyst used in the process is dependent upon the nature and reactivity of the aromatic hydrocarbon undergoing side chain alkylation and upon the nature of the olefin used as alkylating agent. Also the particular acetylenic hydrocarbon catalyst promoter has an influence upon the amount of alkali metal necessary for efiicient operation of the process. In general, from about 0.05 to about 0.5 atomic proportion of alkali metal is present per molecular proportion of alkylaromatic hydrocarbon or other side chain alkylatable hydrocarbon present in the reaction zone. Also from about 0.01 to about 0.05 mol of acetylenic hydrocarbon catalyst promoter is employed per molecular proportion of alkylaromatic hydrocarbon present in the reaction zone.

In carrying out the process the olefinic hydrocarbon charged such as ethylene may be introduced continuously or intermittently, the latter method being commonly employed in the usual type of batch operation conducted in an autoclaveso that the consumption of ethylene can be followed by observing the decrease in operating pressure of the autoclave as the reaction After the reaction has reached the desired stage of completion, the reaction products-are discharged from the autoclave, uncon to a nuclear carbon atom a carbon atom of a saturated hydrocarbon group and to which last named carbon atom is attached at least one hydrogen atom at a condensation temperature in the presence of a catalyst comprising essentially an alkali metal and a monoalkyl acetylene, and recovering a longer chain benzene hydrocarbon from the resultant reaction product.

7. A process for producing a longer chain benzene hydrocarbon which comprises reacting ethylene and a benzene hydrocarbon having attached to a nuclear carbon atom a carbon atom of a saturated hydrocarbon group and to which last named carbon atom is attached at least one hydrogen atom at a condensation temperature in the presence of a catalyst comprising essentially sodium and a monoalkyl acetylene, and recovering a longer chain benzene hydrocarbon from the resultant reaction products.

8. A process for producing normal propylbenzene which comprises reacting ethylene and toluene at a condensation temperature in the presence of a catalyst comprising essentially sodium and an acetylenic hydrocarbon, and recovering normal propylbenzene from the resultant reaction product.

9. A process for producing normal propylbenzene which comprises reacting ethylene and toluene at a condensation temperature in the presence of a catalyst comprising essentially sodium and acetylene, and recovering normal propylbenzene from the resultant reaction product.

10. A process for producing normal propylbenzene which comprises reacting ethylene and toluene at a condensation temperature in the pres ence of a catalyst comprising essentially sodium and a monoalkyl acetylene, and recovering normal propylbenzene from the resultant reaction product.

11. A process for producing a higher molecular weight aromatic compound which comprises reacting an alkene and an aromatic compound having attached to a nuclear carbon atom a carbon atom of a saturated hydrocarbon group and to which last named carbon atom is attached at least one hydroge atom, the process being carried out at a temperature of from about 100 to about 350 C. in the presence of an alkali metal and an acetylenic hydrocarbon containing the CECH group, and recovering the resultant condensation product.

12. A process for producing a higher molecular weight aromatic compound which comprises reacting ethylene and an aromatic compound hav- 10 ing attached to a nuclear carbon atom a carbon atom of a saturated hydrocarbon group.

13. A process for producing normal propylbenzene which comprises reacting ethylene and toluene at a temperature of from about to about 350 C. in the presence of a catalyst comprising essentially an alkali metal and a monoalkyl acetylenic hydrocarbon, and recovering normal propylbenzene from the resultant reaction product.

14. A process for producing normal propylbenzene which comprises reacting ethylene and toluene at a temperature of from about C. to about 275 C. in the presence of a catalyst comprising essentially an alkali metal and a monoalkyl acetylenic hydrocarbon, and recovering normal propylbenzene from the resultant re action product.

15. A process for producing normal propylbenzene which comprises reacting ethylene and toluene at a temperature of from about 125 to about 275 C. in the presence of a catalyst comprising essentially sodium and l-heptyne, and recovering normal propylbenzene from the resultant reaction product.

16. In the side chain alkylation of an aromatic compound having attached to a nuclear carbon atom thereof a carbon atom of a saturated hydrocarbon group and to which last-named carbon atom is attached at least one hydrogen atom, the improvement which comprises elfecting the side chain alkylation reaction in the presence of an alkali metal and an acetylenic hydrocarbon.

17. In the side chain alkylation of an aromatic compound having attached to a nuclear carbon atom thereof a carbon atom of a saturated hydrocarbon group and to which last-named carbon atom is attached at least one hydrogen atom, the improvement which comprises effecting the side chain alkylation reaction in the presence of an alkali metal and an acetylenic hydrocarbon reactable with said metal to form an alkali metal acetylide.

HERMAN PINES. VLADIMIR N. IPATIEFF.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,088,500 Waterman July 27, 1937 2,448,641 Whitman Sept. 7, 1948 2,513,180 Kemp June 27, 1950 2,548,803 Little, Jr Apr. 10, 1951 

16. IN THE SIDE CHAIN ALKYLATION OF AN AROMATIC COMPOUND HAVING ATTACHED TO A NUCLEAR CARBON ATOM THEREOF A CARBON ATOM OF A SATURATED HYDROCARBON GROUP AND TO WHICH LAST-NAMED CARBON ATOM IS ATTACHED AT LEAST ONE HYDROGEN ATOM, THE IMPROVEMENT WHICH COMPRISES EFFECTING THE SIDE CHAIN ALKYLATION REACTION IN THE PRESENCE OF AN ALKALI METAL AND AN ACETYLENIC HYDROCARBON. 